Power electronic devices in a lower power range (e.g. devices with power ratings less than about 50 kW) are often based on printed circuit board (PCB) constructions. Traces of both a main power circuit and signal electronics may be integrated into the PCB. Electrical components, such as semiconductor switches, passive components, and integrated circuits (IC), are typically attached to the surface of the PCB by soldering. By using PCBs, mass production costs may be reduced, while device compactness may be increased.
As more components are integrated to PCBs, power dissipation per area unit of the PCBs also increases. Further, components on a PCB may have diverse cooling demands, particularly if the PCB comprises embedded power semiconductors. As a result, localized hot spots may appear on the PCB. FIG. 1 shows an exemplary embodiment of a typical three-phase inverter module configuration containing six IGBTs 11 and six diodes 12, where each chip is sintered to one surface of a copper substrate. In FIG. 1, fixed, uniform cooling conditions (6000 W/cm2K) were applied to the opposite surface of the package. Despite the high cooling rate, hot spots were prevalent in the package due to the non-uniform heat dissipation between the IGBTs and the diodes.
Non-uniform thermal conditions may induce thermal stresses and thermal fatigue in a PCB package over the lifetime of the package, which may lead to mechanical failures, such as delamination or cracking.
Microfluidic interlayers have been considered in some thermal management areas (e.g. electronics packaging and photonics) where high heat transfer coefficients and a local hot spot management are primary requirements. However, microchannels may be complex to manufacture. Further, microchannel implementations often relate to specific module/package designs and may not be implementable as such to other package designs.